New wheels/tires

I have a bone stock 99 chevy silverado (Not z71) 2wd. I am looking for a new set of tires for it and was wondering the max size tire I can put on it. I am also looking for new wheels, Needing to know a good size rim and what the lugnut spacing is.

I just did all of that (new wheels, tires, and even lugs) and I found every scrap of the information you just asked for between this forum and Google ... by using the 'search' features offered by both. I'm not trying to be a jerk, I'm just trying to suggest that a little effort on your part can go a long, long way.